A Thin Film Transistor Liquid Crystal Display (TFT-LCD) is a display manner used widely currently. FIG. 1 is a block diagram illustrating a driving circuit of an existing thin film transistor liquid crystal display, and as illustrated in FIG. 1, the driving circuit comprises: a timing controller (TCON), a source driver, a gate driver and a gray scale voltage generator. The timing controller sends gray scale data signals RGB, a polarity inversion signal POL, a latch signal TP to the source driver, sends a frame start signal STV, a clock signal CPV and an output enable signal OE to the gate driver. The gate driver and the source driver output row signals and column signals, respectively, so as to control a liquid crystal display panel (LCD panel) to display.
The liquid crystal display is of a voltage driving type, that is, a transmittance of a liquid crystal box is controlled by applying different voltages at two terminals of the liquid crystal box, so as to implement the display. Each of pixels is generally divided into R sub-pixel, G sub-pixel and B sub-pixel, wherein one terminal of each of the sub-pixels is a common potential to which a same voltage referred to as a common voltage Vcom is applied, and the other terminal of each of the sub-pixels is a pixel voltage supplied by the source driver. If the voltages applied to the liquid crystal box remain a same polarity, the liquid crystal would be polarized and fail to operate, therefore the liquid crystal driving is implemented by polarity inversion schemes. If a pixel voltage is smaller than the common voltage Vcom, it is referred to as a negative polarity driving; if the pixel voltage is greater than the common voltage Vcom, it is referred to as a positive polarity driving. Manners of the polarity inversion are varied, such as a frame inversion, a row inversion, a column inversion, a point inversion, etc. As illustrated in FIG. 2, which is a schematic diagram of an existing point inversion driving manner, the driving polarities of adjacent sub-pixels are opposite. In particular, in the Nth frame, the polarity of the sub-pixel at the first column of the first row is + (positive polarity driving), the polarity of the sub-pixel at the second column of the first row is − (negative polarity driving), the polarity of the sub-pixel at the third column of the first row is + (positive polarity driving), and so on; the polarity of the sub-pixel at the first column of the second row is −, the polarity of the sub-pixel at the second column of the second row is +, the polarity of the sub-pixel at the third column of the second row is −, and so on; and at the next frame (the (N+1)th frame), the polarities of the all sub-pixels in the (N+1)th frame are opposite to those of the corresponding sub-pixels in the Nth frame. Such driving manner is optimal for a picture quality because the polarity in the entire picture reaches a balance.
However a case of polarity unbalance may still occur in same special pictures and cause a phenomenon of green attachment. For example, when a window picture is displayed, colors at two sides of the window may different from colors at other positions, that is, a so-called lateral crosstalk occurs. Generation reasons for such phenomenon are as follows: the liquid crystal display adopts a row scan manner, when gates of one row are turned on, the pixel voltages of all sub-pixels are written to the respective sub-pixels through respective data electrodes, but a coupling capacitor exists between each of the data electrodes and the Vcom electrode, such that a capacitor coupling effect would occur and pull up or down the Vcom voltage if the pixel voltages of the one row are unbalanced, which may cause errors in voltages written actually. As illustrated in FIG. 3, the point inversion driving manner is adopted, but amplitudes of the gray scale voltages at the two adjacent pixels are different, such that the pixel voltages on the first row are negative entirely and pull down the Vcom voltage, while the pixel voltages on the second row are positive entirely and pull up the Vcom voltage. Since the Vcom is a reference common voltage, its deviation may lead to errors in the actual voltage across the pixel.